is just me or voice IP sucks?

I wouldn't say netcode of the game should have ANY influence on voice at all. In most games voice chat is going through a different server. E.g., in multiple cases of PubG games the game itself froze (noone could move, disconnected sign), but talking to teammates worked just fine - different servers. On the other hand, this may not be the case for Apex, which would explain why voice quality is so inconsistent in this game - game server lagging a bit would result in voice lagging a lot (since voice most obviously would have lowest priority if it was sent through the same server).

Also, voice seemed to be just fine at start, but after one of the early updates (a month or two after release) it just got A LOT worse (just after update the quality was completely terrible and the sound volume on max was way too silent) and never reached the initial quality after that. I have no idea what that was about, since there never anything about it in the patch notes. It's usually fine now, but still quite often a bit too silent and quality is inconsistent.